The wavelength of ultraviolet (UV) radiation is smaller than 400 nm. Semiconductor devices that are used for the detection of ultraviolet radiation require a voltage supply for the registration of received doses of ultraviolet radiation. An ultraviolet sensor device may also require a UV filter comprising a material that is not available in a standard CMOS process. An ultraviolet sensor device that is fully CMOS compatible is desired for an extended range of applications, especially in mobile computing devices, for instance.
JP S 57-40619 A discloses a light detection system comprising a MOSFET structure with a floating gate electrode. Charge is accumulated on the floating gate electrode by hot carrier injection generated by an application of a sufficiently high voltage between source and drain. UV irradiation causes the charge to dissipate, and this effect can be detected by an electronic circuit, because the working point of the MOSFET depends on the amount of charge stored on the gate electrode.
FR 2911191 A1 discloses a device for measuring a dose of ultraviolet radiation. The device comprises a MOSFET with a gate electrode and a floating gate electrode. A voltage is applied between the gate electrode and the drain in order to accumulate electrons on the floating gate electrode and thus increase the threshold voltage. UV irradiation causes a dissipation of the electrons, and the resulting change of the threshold voltage is detected by measuring the drain current before and after the UV irradiation.
US 2013/0020477 A1 discloses an ultraviolet radiation measurement sensor comprising an integrated circuit, a transparent window and a plurality of transistors with floating gates to be programmed by an injection of hot carriers. The transistors are arranged according to a non-volatile memory and provided with a device for programming, reading and/or erasing.
US 2008/0218755 A1 discloses semiconductor UV absorptive photometric cells comprising a floating-gate EPROM device. A central polysilicon floating gate electrode is laterally surrounded by a control gate, which has a subsurface electrode shared with an adjacent control transistor.
U.S. Pat. No. 5,504,706 A discloses a low voltage flash EEPROM memory array. The memory cells are fabricated from a single poly layer floating gate and are operated in accordance with Fowler-Nordheim tunneling.
US 2005/0213391 A1 discloses a block alterable EEPROM cell. A layer sequence comprising a tunnel oxide, a poly floating gate electrode, an oxide interlayer and a poly control gate electrode extending over the floating gate to an edge of a drain implant region are arranged on a substrate. Fowler-Nordheim tunneling is used to program and erase the cell.
WO 91/11026 A1 discloses a non-volatile electrically alterable semiconductor memory device with a re-crystallized floating gate electrode. A control gate electrode, which is insulated from the floating gate electrode, is arranged laterally, and partially overlies the floating gate electrode. The cell is programmed by channel hot electron injection and is erased by Fowler-Nordheim tunneling.
WO 00/59032 A1 discloses a non-volatile memory, which is implemented in a double polysilicon process. Channel hot electron injection onto a floating gate electrode is used for programming. The erasure of the memory cell is effected by Fowler-Nordheim tunneling of electrons from the floating gate electrode to the channel region and to the drain diffusion.
JP H01 307627 A discloses an ultraviolet-ray sensor comprising a source area, a drain area, a control gate area formed in a semiconductor substrate, and a floating gate electrode embedded in an insulator above the substrate. The floating gate electrode is exposed to ultraviolet rays.
U.S. Pat. No. 6,972,457 B1 discloses an imaging cell with an EPROM structure comprising a floating gate electrode formed from a layer of patterned polysilicon approximately 200 nm thick, which extends over an area of a control gate region formed in the substrate.
US 2008/0218755 A1 discloses semiconductor UV absorptive photometric cells comprising a floating-gate EPROM device. A central polysilicon floating gate electrode is laterally surrounded by a control gate, which has a subsurface electrode shared with an adjacent control transistor.
US 2005/0230271 A1 discloses floating gate field effect transistors for chemical and/or biological sensing. A floating gate electrode is arranged between a control gate electrode and the substrate.